Fire control means fob aircraft



M. F. KETAY FIRE! CONTROL MEANS FOR AIRCRAFT GUN. MOUNTS 2 Sheets-S heet 1 Filed Dec. 14, 1939 lNjgNTOR Oct. 21, 1947. M. F. KE' IAY FIRE CONTROL MEANS FOR AIRCRAFT GUNMOUNTS Filed Dec. 14, 1939 2 Sheets-Sht 2 iNVENTbR ATTORNEY l'The above Patented Oct. 21, 1947 FIRE CONTROL MEANS FOR AIRCRAFT GUN MOUNTS 7 Morris F. Ketay, Brooklyn,

Bendix Aviation Corporation,

N. Y., assignor to South Bend, Ind.,

a corporation of Delaware Application December 14, 1939, Serial No. 309,163

6 Claims.

This invention relates to a fire control system, and moreparticularly to means for controlling a gun, the sights for the gun, and a turret in which the gun is mounted.

In modern aircraft it is desirable, in certain instances, to mount one or two machine guns, for example, in a turret in such a manner that a single operator can control the laying and firing of the gun or guns. The present invention, which is particularly adapted for aircraft uses, embodies novel methods and means whereby certain ballistic corrections are automatically applied to the gun sights as the gunner brings th'e gun to bear on the target.

Another object of the invention is to provide novel means whereby turret and gun may be rapidly 'moved or slowly moved as the gunner may desire to bring the gun or guns to train on the target.

A further object of the invention is to provide a fire control system which is so constructed that the gun and turret are rapidly moved in elevation and azimuth while the gunner moves himself in accordance with the movement of the gun and turret. g

Another object is to provide a novel follow-up fire control system which lends itself to one-man control. p I

I and other objects will appear more fully hereafter in the detailed description which is to be read with the accompanying drawings. n will be understood that the drawings and the description are directed to those skilled in the art and that various changes may be made in the mechanical and electrical details, the drawings serving primarily to illustrate the electrical circuits which may be employed. In the drawings,

Fig. l is a diagrammatic showing of one embodiment of the present invention, certain mechanical details well understood in the art being omitted in the interest of clarity;

Fig. 2 is an enlarged detail taken on the line '2'- 2 of Fig. 1, and

Fig.3 is a diagrammatic illustration of a second embodiment of the invention.

Figure 4 shows an aircraft with the fire control mechanism mounted thereon. As shown in Fig. 1', the system comprises a turret 3 adapted to be rotatably mounted on the upper portion of the fuselage of an airplane in any suitable manner. The turret is provided with an aperture 4 having an angular length of approximately and through this aperture extendsthe muzzle portion of a gun 5 adapted to be elevated and depressed in a vertical plane relative to the turret.

Preferably, the turret is not provided with a floor, the gunner supporting himself on the airplane structure within the turret. It will be understood that the turret and gun are not to scale and the remaining elements shown are on a much larger scale than the gun and turret. It will also be understood that more than one gun may be mounted in the turret if desired.

Novel means are provided to rotate the turret in azimuth or to train the turret. For this purpose there is provided a power motor 6 having directional fields 1 and 8, which motor is adapted to rotate a gear 9 meshing with a ring gear [0 0n the turret. Current to the armature of motor 6 is controlled by means of the solenoid ll.

Novel means are provided for elevating and depressing the gun 5, said means including a motor [2, the flow of current for the armature of said motor being controlled by solenoid l3. Motor l2 is provided with a field M for securing rotation of its armature in one direction and with a field l5 for securing rotation of the armature in the opposite direction. The motor drives a gear It in any suitable manner to actuate a gear l'l operatively connected to gun 5 to move the same in a vertical plane about trunnions not shown. 7

Novel means are provided for selectively controlling the fiow of current to directional fields 1, 8, I4 and I5 whereby turret and gun may be moved in the desired direction and at varying rates of speed as desired by the gunner. For this purpose there is provided a rod like control member l8 which is mounted on the airplane in a position convenient to the gunner and preferably in such a manner that said member can be freely moved in any direction about two axes. Operatively connected to member [8 are slotted horizontal and vertical (as viewed in Fig. 1) crossarms 19 and 20, respectively, which are mounted for movement with member [8. Arms l9 and 20 are adapted to control four pairs of contacts 2|, 2'2, 23 and 24, a very slight movement of control member l8 from its central position being eifective to close one or more of the pairs of contacts. Arm 20 is also operatively connected through any suitable mechanism 25 to a brush 26 movable longitudinally along the commutator 21 of a small constant speed motor 28. Arm I9 is adapted to move, through suitable mechanism 29, a brush 30 which also engages commutator .21. The latter is provided with a plurality of triangularly shaped insulating segments 3|, the bases of said segment being preferably disposed adjacent one end of the commutator with-the apices of :the triangularasegments extending for a distance along the length of the commutator and being equi-spaced about the periphery thereof. A suitable source of power, such as a generator or battery (not shown) is operatively connected to leads 32 and 33 for supplying current to motors 6, l2 and 28.

If control member I8 is moved-byxthe gunner from its central position to the right, for example, so that the longitudinal aXis of the control member is maintained in a vertical plane'passing through the center of arm l9, contacts .2la vill be closed and brush 26 will-be moved along the commutator toward the apices. of theinsulating .triangles. Current maynowfflowflthrough' 1ead132 and'through .lead 34 to a brush 35 on commutator'21, through the conductingportionI 3 laeof. the commutator and intermittently through. brush 26 and lead'36to the directionalfield. 8 of .motor 6. From thence .the circuitfiows throughcontacts'f2l and, then backto the. positive side 33 .of the, power line. .QSincebrush 26, in the-position illustrated, has. engagement withthebasesof triangle. 3 I, current .iflows intermittently through the circuit and; .hencev thearmature. of motor 6 rotates .at .low speed to .drive..gear;.9. and' ring. gear I thereby, training the. turret..slowly..to.the right. When brush; 26 is moved .downwardlyalongthe commutator, aswhen member I 8. is-moved to the right through .a. largeangulardistance, .the. ratio ofthetimeof power on topower off in- .creases,.--and .may. reachta point whenpowerwill be ffon continuously, whereupon motor. 6 is effective .to. train theturret at higher .speeds.

If control member I8 is moved to the right from the vertical position illustrated and. .substantially at a 45 angle upwardly. relativeto the longitudinal axis of arm 1-9, the-latter is moved upwardly from! the position shownin Fig. 1 while arm .20 .is moved to the right, thereby closing (contacts v2 I and. 22 and moving: brushes. 25 and 30 downwardly=al0ng commutator =27. =Current nowaflows through directional field 8 and the armature of motor 6,-.as just described, but as .soon as :brush .26 :has been moved downwardly along the commutator. more. power flows through brush 35, through conducting portion 3la to brush :26 whereby the 'speedof motor 6 is-increasedand the speed of train oftheturretis likewise increased. At thesametime current can flow through commutator 21 tobrush 3D, lead-38, directional field -l of motor l2, lead 39, contacts 2 2 and. back -to supplyline -33. When contacts 22 are closedtheyf-also .energize. solenoid 3 l3 which, inv turn, energizesthe armature of motor l2. :Ro- .tation of thearmatureof motor .12 isnowefiective throughgearslfi and l ltoeelevate -gun 5.

=If controlmember I 3 is moved downwardly and .to the left-froma-the position illustrated in Fig.1,

contacts 23an-d 24 WilLbe closed and brushes-30 and 26 will be moveddownwardly-along commu- -tator.21. .Directional field l-of. motorfi willnow be energized to trainthe .turret, in the opposite direction and directional field M of motor l2 will be energized whereby the muzzle of the gun will be lowered rather than elevated. The angular movement of the control member determines the 5 relative positions of brushes 26 and 30 and hence power motors 6 and I2 must flow through commutator 21 it is chopped up (except when brushes 26- and .30 arein maximum. speed position) butthe inertia of the-motorarmature and of the turret tends to iron out the intermittent .-mo-tion imparted to the gun or turret and smooth operation at any suitable speed may be obtained. The5gunneristhus enabled quickly to train and -elevate his gun to bring the same to bear on his .target. 320 Due ;to the relative movement between the gun 1 aniditarget,-:;cert;ain corrections must be applied to the gun sight, in order to insure a hit. These corrections are-usually-applied by moving. the sight relative to the gun. A relatively movable sight is complicated. The interval of time available on aircraft v for .making range. and deflection. corrections is extremely limited andthe numbenof then available for. fire control is .alsolimited. Accord ingly, to secure the best results foraviationpurposes .all corrections, such.asiare..normally employed in naval. gunnery, for, .example,.. cannot .be satisfactorily applied. to the sights and thepresent invention .providesautomatic corrections'l'for thefactors which give the.largest errors. More- .35 over, these correctionsarepreferably. applied;-to

the cross-Wires. of. the sight andlthel sight. is. stationary. relativeto. the gun barrel. .-.As "shown, sighting telescope 42 is. rigidlyrmounte'duon.gun i and the cross-wires'thereof (Fig. .2)..are'operatively .connected tomagnetic vcompensators5a.

,and.5b.which in turnare conneotedtof 2. Wheatstonebridge, the compensator 56 for the. horizontal cross-.wire. in .the sight being connected by leads'45 to a Wheatstone bridge46 While theco .pensator .-5a-.for. theverticalwire .of thejsight is connected through leads-T43 to .Wheatstone' bridge '44. .Qperatively connected .to the -.Wheatstone bridges are air speed. generators .41 .and -.48, ..respectively, the output of. eachof these. generators 50 being a function of the altitude and speed .ofQthe aircraft. In certain. instances,- only .oneairLspeed generator. .operatively connected to'. both bridges M and "46 may be employed. The Wheatst'one bridges are. also.provided with movable contacts .49 and .50, respectively, which are aactuatedkby any suitable mechanisms 5| and 52, mechanism ,5Lbeing operatively connected to a cam 53rwhich rotates with the turret and mechanism :52 being opera-tively connected to a cam -53a.which rotates withthe gun. Since theprimary.windage-correctiondepends upon .the angle of the longitudinal-:axis'ofthegunto theline of fiightofthe-aircraft the altitudeat whichthe craft is flying and its speed, arms 49- and :50 control the output of the bridge circuits. to correct for the gurr position relative to the longitudinal axis of the aircraft, whereas generators-Aland 48 correct tort-altitude and speed. It is also desirable to apply a f-gun lead correction tothe cross-wires and thiscor- .70 rection is a function of the rate atwhichthezgun or theturret and gunare angularly moving relative to the fuselage. To apply this correction vthere .are provided. generators 54 and -.5-5e.driven by. motorss 'and- I 2,. respectively, throughsuitable mechanical connections, said generators being tionary transformer.

operatively connected to bridges 4'4 and 46 whereby the output of generators 54 and 55 are algebraically added to the other corrections and are fed through leads 43 and 45 to the magnetic compensators controlling the positions of the crosswires in sight 42.

In certain installations it is desirable to provide a follow-up control system. Such a systern is illustrated in Fig. 3 wherein control member 18 and arms l9 and 26 are effective to move primary rotors 56 and 51 to the position desired by the gunner to secure the proper train and elevation of the gun or guns. The primary rotors are operatively associated with 3-phase transformer secondaries 58 and 59 which latter are connected in the usual manner to the 3- phase primaries 60 and 6| of other control transformers having movable secondaries 62 and 63 respectively. The secondaries are operatively connected in the usual manner to stationary transformers having primaries 64 and 65, respectively, and secondaries 66 and 61, respectively. Preferably, transformer 66-62 and 6 l-63 and the associated stationary transformers are mounted at any suitable place in the airplane near the turret while transformers 56-58 and 51-59 and the remaining mechanism to be described, with the exception of the power supplies, are mounted within and movable with the turret. The two stationary transformers are operatively connected with the grids and filaments of vacuum tubes 68 and 69, two vacuum tubes being provided for the output of each sta- Tubes 68 and 69 feed the differential fields 10 and 1| of small control motors 12 and 13. The armatures of these motors are operatively connected through leads 12a, 13a to a source of D. C. current and in operation, the armature is continuously on the D. C. line. The control motors are also provided with differential fields 14 and 15, respectively, which are connected through potentiometers 16 and 11 to the D. C. supply. The movable arms of the potentiometers are adapted to be actuated by motors 12 and 13 through connections 92, 93, respectively and preferably, said arms are mechanically or otherwise suitably connected through connections 94, 95 to brushes 18 and 19 having engagement with a commutator 89 of a constant speed motor 8| operatively connected with the D. C. supply. The commutator is quite similar to that described above in Fig. 1 except that preferably two series of insulating triangles are provided, the bases of each series being adjacent the center of the commutator with the apices of the triangles of each series extending toward the ends of the commutator.

Any movements of the armatures of motor 12 and 13 are effective to close contacts 82 and 83, respectively, contacts 82 being in circuit with brush 18 and through commutator 86 with a brush 80a which is in circuit with the D. C. supply. When contacts 82 are closed they are also in circuit with a directional field 84 for a power motor having an armature 84a, which armature is operatively connected through suitable mechanism to a ring gear on the turret. Contacts 83 are in circuit with the difierential field 85 of a power motor having an armature 85a which is operatively connected through suitable mechanism to the elevating gear of the gun, said contacts 83 being adapted to place difierential field 85 in circuit with the D. C. supply through brush 19, commutator 80 and brush 80a.

In addition to the connections referred to,

armature 84a is drivably connected to the secondary 62 of the control transformer by connection diagrammatically illustrated at 96 and armature a. is drivably connected through suitable mechanism diagrammatically indicated at 9| to the secondary 63 of the control transformer 6|, 63.

When the mechanism and circuits just described are operatively connected to control member l8, arms [9 and 20, and to the turret and gun or guns, movement of the control member is efiective through said arms to move th primary rotors 56 and 51 of the control transformers to positions as required by the gunner. This movement unbalances the secondary voltages in the control transformers which unbalance is transmitted to the 3-phase primaries 60 and 6|, whereby the output of the secondaries 62 and 63 may be varied both in magnitude and direction depending entirely upon the deflection or angular movement of control member la. The variation and the output of secondaries 62 in 63 are effective through transformers 64-66 and 65-61 to control the output of the vacuum tubes and hence the direction of current flows through the differential fields 18 and 1|.

The phase and magnitude of the A. C. current through coil 61, for example, is a function of the current through coil 65, which in turn depends upon the location of coil 63. When the latter is in a mean or neutral position, coil 61 is not energized except directly from the power source, and in this event, tubes 69 are balanced. If coil 63 is moved from normal position, it procluces a change in the phase of the current in coil 61 which augments the potential differences across one-half of the coil and decreases the potential differences across the other half of the coil thus unbalancing the grids of tubes 69 relative to their equal filament potentials. The result is an unbalance across coils 1| which unbalance depends in magnitude and direction on the degree and direction of the displacement of coil 63. When the control member I8 is in neutral position fields 1|, 15 and 18, 14 balance out and armature 12 and 13 are stationary with the potentiometer arms 15 and 16 in central position on the associated rheostats. When the control member is moved, however, one or both of the differential fields 10 and H are energized and one or both of the armatures 12 and 13 start to rotate. The armatures are now effective to move the potentiometer arms in such a direction at to balance the fields. However, movement of the armatures was effective to close contacts 82 and 83 so that armature 84a or 85a, or both, is set in rotation, thereby training the turret and elevating the gun or performing both of these operations simultaneously. The rate of movement of the armature 84a and 85a. depend upon the position of brushes 18 and 19 on the spe cial commutator and this position is determined by movement of armatures 12 and 13. Since armatures 84a. and 85a are also drivably connected to secondaries 62 and 63, respectively, of the control transformers, rotation of said armatures is effective to actuate said secondaries to re-establish balanced conditions in the control circuits. The degree of unbalance in secondaries 62 and 63 determines the amount of rotation imparted to the armatures of 84a. and 85a. The movement of the latter, which movement results from the movement of said secondaries, is utilized to rotate and return the secondaries to normal balanced position. This is accomplished 7. in any well-known mechanical'or electrical oneway" driving connection from the armature'to the. respective coils. Thus the result produced by the displacement of coil 63, effects a followup which returns coil 63 to balanced position. When a balance in the control circuits is reached the vacuum tubes ar inelfective to set up a field in either direction for the differential motors and the potentiometer arms are now in central position; No further movement is imparted to either gun or turret until the control member is again moved in the desired direction by the gunner. Ballistic corrections are taken care of inthis embodiment of the invention in the manner described above in connection with Fig. 1.

There is thus provided a novel fire control system which may be embodied in a non-follow-up or follow-up arrangement. The apparatus is simple. in construction and of light weight and is particularly adapted for use in aircraft for one man: operation. Various mechanical elements of the system will readily suggest themselves to those skilled in the art for operatively connecting the various parts and accordingly reference will be had primarily to the appended claims for a definition of the limitsof the invention. It is to be expressly understood that the invention is not limited to aircraft uses, but may be applied to other fire control systems where speed and a minimumof man-power is desired. Moreover, the speed control for the electric power means is adapted for use in many fields and may be embodied in various mechanical forms. While in the embodiment illustrated, said control means are employed for chopping up field current, it will beunderstood that armature current, or both armature and field current, may be controlled by said means.

. What is claimed is:

-1. In' a fire control system for a gun fitted with a gun sight having movable horizontal and vertical cross wires, the combination with said wires of magnetic compensators operatively connected to the wires for moving the same relative to the sight, and means electrically connected to each of said compensators for applying altitude and speed corrections to said cross wires comprising Wheatstone bridges connected in one diagonal to the compensators and wind-driven generators operatively connected to another diagonal of said Wheatstone bridges whereby the voltage imposed by the generators on the bridges varies with the impact of the air on the wind-driven generators.

2. In a fire control apparatus of the type adapted to be mounted and employed upon a vehicle, the combination comprising a gun mount and a gun pivotably and rotatably mounted thereon, a sight for said gun including movable cross hairs and means tomove them to make ballistic corrections, means to move the gun in train relative to the mount, means'to move the gun in elevation relative to the mount, a windd-riven generator adapted to be driven by the flow of air about the vehicle and to respond to the density of the air, a power generator responsive to the said motion of the gun in elevation, a power generator responsive to the said motion of the gun in train, means to combine the power generated by said several generating means including means responsive to the position Of the gun relative to its mount to apply a compensation for said position, and means operable by said combining and compensating means to apply the resultant of the said compensations as ballistic corrections to the cross hairs of the gun sight.

3. In an aircraft, a sightcontrol apparatus for a gun pivotally and rotatably mounted on said aircraft, a sight for said gun mounted on said aircraft, said'sight including movable cross hairs and means to move the cross hairs to make ballistic corrections, means to rotate the gun in either direction relative to the aircraft at any selected speed within the limits of the apparatus, means to change the elevation of the gun relative to the aircraft at any selected speed within the limits of the apparatus, a wind-driven power generator mounted on the aircraft and responsive to the free flow of air about said aircraft and to the density of the air, a power generator responsive to the motion of the gun in elevation, a power generator responsive to the motion of the gun in train, means to combine the power generated by said several power generating means including means responsive to the position of the gun relative to its line of flight to apply compensationfor the angle of the gun to the line of flight, and means operable by said combining and compensating means to apply the resultant of the said compensations as ballistic corrections to the cross hairs of the gun sight.

l. In fire control apparatus for a mobile gun pivotally mounted in a rotatable turret, a gun sight having means to compensate for sighting errors in elevation and in train, electric power generating means responsive to the altitude and speed of the gun, electric power generating means responsive to the motion of the gun in train, electric power generating means responsive to the motion of the gun in elevation, and electric compensating means to combine the electric outputs of said power generating means and to apply the combinations to said means to compensate as ballistic corrections;

5. In fire control apparatus for a pivotally mounted mobile gun, a gun sight having means to compensate for sighting errors, electric power generating means responsive to the altitude and the speed of the gun, electric power generating means responsive to the motionof the gun relative to its mount, and electric means to combine the electric output of said power generating means and to apply the combination to said means to compensate as ballistic corrections.

6. In fire control apparatus for apivotally mounted mobile gun having power means to aim the gun, a gunsight having means to compensate for sighting errors, electric power generating means responsive to the altitude and speed of the gun, electric power generating means responsive to the aiming means, means to combine the electric output of said power generating means and apply the combination as a ballistic correction to the compensating means of the gunsight, and means responsive to the position of the gun relative to its mount to vary the ballistic correction imposed upon the compensating means of the gunsight.

MORRIS F. KETAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number ((tther references on following page) 

